Synthesis, characterization, and electrochemistry of monophosphine‐containing diiron propane‐1,2‐dithiolate complexes related to the active site of [FeFe]‐hydrogenases

Abstract

Five monophosphine‐substituted diiron propane‐1,2‐dithiolate complexes as the active site models of [FeFe]‐hydrogenases have been synthesized and characterized. Reactions of complex [Fe 2 (CO) 6 {μ‐SCH 2 CH(CH 3 )S}] ( 1 ) with a monophosphine ligand tris(4‐methylphenyl)phosphine, diphenyl‐2‐pyridylphosphine, tris(4‐chlorophenyl)phosphine, triphenylphosphine, or tris(4‐fluorophenyl)phosphine in the presence of the oxidative agent Me 3 NO·2H 2 O gave the monophosphine‐substituted diiron complexes [Fe 2 (CO) 5 (L){μ‐SCH 2 CH(CH 3 )S}] [L = P(4‐C 6 H 4 CH 3 ) 3 , 2 ; Ph 2 P(2‐C 5 H 4 N), 3 ; P(4‐C 6 H 4 Cl) 3 , 4 ; PPh 3 , 5 ; P(4‐C 6 H 4 F) 3 , 6 ] in 81%–94% yields. Complexes 2 – 6 have been characterized by elemental analysis, spectroscopy, and X‐ray crystallography. In addition, electrochemical studies revealed that these complexes can catalyze the reduction of protons to H 2 in the presence of HOAc.